Plot a vertical ligne from the maximum of a function

Hi, Let say that I have a function f(x) and x=[x1,x2,...,xn] the values that can x take it, so for example if f(x) reach a maximum at x5. How can I plot a vertical line from the maximum point in the plot of the function f(x) to x5 in x axis.

Answer 1

[Image Analyst]

Assuming x5 is the index of your vector "f" where the line should be drawn, try this:

[yMax, xMax] = max(f); % xMax is an integer index 1,2,3, or 4,.....not a floating point value.
yl = ylim();
line([xMax, xMax], [yl(1), yMax], 'Color', 'b', 'LineWidth', 2);
grid on;